Cats raised as pets are particularly susceptible to kidney disease once they become old. Cat kidney disease ranks as the highest cause of death among cats, and thus early diagnosis thereof is an important issue for small animal veterinarians at clinical sites. In the case of humans, the levels of proteins excreted in urine are measured for initial diagnosis of kidney disease. Proteinuria is used as a diagnostic marker for early warning of kidney abnormalities. However, in the case of cats, cauxin (carboxylesterase-like urinary excreted protein), which is a kidney-derived protein and a kind of carboxylesterase that has a molecular weight of 70 kDa, is present at a high concentration in urine, even in the cases of healthy cats. Hence, physiological proteinuria (Cauxin urine) and pathological proteinuria are indistinguishable with the use of a commercially available urine test paper strip. The concentration of cauxin in cat urine is as high as 0.50 g/L, and a cat excretes 100 mg of cauxin a day.
Therefore, diagnosis of cat kidney disease requires the removal of cauxin from urine, and thus a pretreatment material therefor is required.
A method using lectin that specifically binds to the sugar chain of cauxin has been reported as a method for removing cauxin from cat urine (see Patent Document 1).